Telephone switch utilizing a multielectrode gaseous discharge tube



March 18, 1952 w. HULLEGARD 2,589,697

TELEPHONE SWITCH UTILIZING A MULTIELECTRODE GASEOUS DISCHARGE TUBE FiledOct. 21, 1946 I Z l T ,Ig/v /6 2/ 11/ 2/" [v INVENTbR.

[7235 h /demar Hal/991d Z BY W Patented Mar. 18, 1952 1 ELEPHONE SWITCHUTILIZING A MULTI- ELECT-RODE LG'ASEOUS DISCHARGE TUBE ..Erik"-WaldemarYHu'llegard, Stockholm, Sweden, 'Iassignor'jto .Telefonaktiebolaget L.M. Ericsson, Stockholm,LSweden, a company ofSweden :AppIicationtOctober21, 1946, Serial No. 704,745 lnrswe'den November 12, 1945 1"Claim. J1

The present invention relates to a connecting device containinggaseousdischarge tubes having a plurality of electrodes, and '-isparticularly intended for line finding purposes in automatictelephoneplants or the like.

The electrontube in a deviceaccording toethe invention consists of-agaseous discharge tube having a plurality cf electrodes whicharesoarranged that a plurality of separate discharge chambers areobtained within the tube, which chambers are separated from each othervin-such a Way that a discharge in onechamber does not substantiallyinfluence the electric properties of other discharge chambers.

The electron tube is providedwith an electrode common to several orall-of the-discharge paths in the tube which paths are shielded fromeach other and from the surroundings. In this case the common electrodeis suitably so formed that it simultaneously will serve as a shieldbetween the diiferent discharge paths; for instance a honeycomb likearrangement, in the hollow spaces of which the other electrodes areplaced. The common electrode may suitably .be further closedby meansofan insulating .discon that side where the connections to the otherelectrodes v are inserted and by another insulating disc or ametal discon the opposite side.

The inlet openings of the.insulating-discare desirably made so largethat leakage from the.

disc surface to the lead-in wires is prevented.

In most cases the tubes will be constructed for connection in the usualmanner to a tube socket. It may then be suitable to form thoseelectrodes which are intended to be anodes-provided that the anode doesnot constitute the shieldingelectrode-in such a way that they will passthrough the tube envelope and at the same time form base pins.Electrodes, which are intended to be used as cathodes, may under thesame conditions suitably consist of small plates attached to the basepins inside the tube envelope.

In the appended drawings, Figure 1 shows schematically a tube for use ina device according to the invention,

Figure 2 is a perspective view of the tube, and

Figure 3 indicates schematically a connecting device utilizing tubesaccording to the invention.

In Figs. 1 and 2 the envelope of the electron tube is indicated by I,the electrodes in each of seven discharge paths by 2 and the partitionwalls between'the different discharge paths by l. The electrodes can bearranged so that they can be brought out directly through the envelope(perpendicularly to the plane of the drawing in Fig.

1) and at the same timeserve as base pins for connection with lead-inwires 2d of a common tube socket 23 having eight contacts.

The tube has an electrode 7 common toall discharge paths. The commonelectrode is arranged so .that it shields the other electrodes from oneanother, separate discharge spaces thereby being obtained between thecommon electrode and each individual-one or" the'remaining electrodes.For further shielding of the discharge paths, mica plates 22 arearranged at one or both ends of the common electrode In the drawing, thecommon electrode is formed of radially placed plates 1, which divide thetube into seven different discharge spaces, each containing one of theotherv electrodes.

In Fig. 3 a connecting device according-to the invention is shownschematically, forinstance a line finder, in which tubes of the kinddescribed above are used. Four tubes are indicated ll-l i in thedrawing, each provided with a cathode (or anode) l2l2 andfour anodes (orcathodes) l3'-l3 Each of the four'anodes in each tube is connected toone of four conductors it, i5, 1%, il each connected with an impedanceIt. Each cathode l2'l2 is connectable to an electrical device I'd-49 ofan arbitrary-kind over a contacttiY-ilt and over an impedance 2l'--2l"which device is desired to be connected to any one of the conductorsit, it, it, il', when the contacts 26', 28'', Zii and ZQ respectively,of the device is closed, yet so, that a communication cannot be obtainedwith a conductor connected with another device E8. The devices E9 to Hand the contacts 2% to 28 are not shown in detail since their structureforms no part of the present invention. They may form part of atelephone switching system of known kind in which devices it to NE areselection stages and contacts 2% to 26 are controlled to establish aselected communication channel. Such a connection is procured by thetubes i i in the following manner: on closing (for instance) the contact20', a voltage is obtained over the cathode-anode paths in the tube iicorresponding to the full voltage between the terminals of a currentsource (-I- and in the figure). This voltage is higher than the ignitionvoltage of the tubes. Due to this a discharge starts between theelectrode l2 and an arbitrary electrode 53. At the same time, however,by a suitable choice of voltage and impedances 2| the voltage across thetube between the electrode l2 and the remaining electrodes 13 (due tothe voltage drop in the impedance 2 1') becomes so low that furtherpaths cannot be ignited. In the figure the discharge obtained isindicated by a full arrow in the tube H. The device I9 is then connectedover the discharge path to the wire [5, which due to the voltage drop inthe impedance l8, acquires a lower potential than the wires l4, l6 andI1. If now (for instance) the contact 2I" is closed, the full voltage ofthe current source will be obtained between the electrode I2 and thoseelectrodes l3' which are not connected to wire IS. A discharge of thetube may therefore only take place over some of these idle electrodes,and thus the device 13" is connected with a free wire. .Otherwise theprocess becomes the same as before. If

a discharge thereafter occurs for example in the electrode path markedwith adotted arrow, the device l9' is connected to the wire 16 and onlythe wires 14 and H are thereafter free for connection to a furtherdevice I3.

The invention is of course not limited to connections according to Fig.3, and the tubes present quite especial advantages for all kinds of linefinders and the like due to the fact that 00.1 plicated mechanicalconstructions are replaced by tubes having no movable parts whatever.

I claim:

In a connecting device for automatic telephone plants or the like of thetype which includes a plurality of gaseous discharge tubes for effectingconnections between certain incoming lines to certain outgoing lines,each of said discharge tubes having an impedance connected in seriestherewith and with anincoming line and a second impedance in series witheach of said outgoing lines, the improvement which comprisesconstituting each of said dischargetubes by a common envelope containinga common gas atmosphere a plurality of electrodes and a singlecounter-electrode common to all said electrodes, wherein saidcounter-electrode is arranged to shield said other electrodesfrom eachother and disposed so as to dividethe gas atmosphere within saidenvelope ,into a number of different discharge chambers each containingone of said electrodes so as to prevent the discharge in one of saidchambers from influencing the electric properties of the other dischargechambers, a number of incoming lines each connectable to thecounter-electrode of one of said tubes, 2.

number of outgoing lines connected to one of said other electrodes ineach of said tubes, an impedance in series between eachcounter-electrode and each incoming line, a second impedance in serieswith each of saidoutgoing lines, a contact for connecting each incomingline to the corresponding counter-electrode, and a current source onepole of which is connected with each in coming line and the other poleof which is connected with said second impedances, the voltage of saidcurrent source being such as to produce ignition between saidcounter-electrodes and one of said other electrodes immediately uponclosing of the contact in series with the counterelectrode in question,whereby the corresponding incoming line is connected to the outgoingline belonging to said other electrode over a path including saidcontact, said first impedance and the discharge between saidcounter-electrode and said other electrode in question; the voltage dropin said first impedance preventing the ignition of the other dischargepaths between said counter-electrode and the other electrodes in saidtube, and the voltage drop in the second impedance connected to theoutgoing line in question reducing the potential of this line in such away that the potential of all electrodes in other tubes connected withthe same outgoing line is insufiicient for producing ignition betweenthese electrodes and the counter-electrode on connecting anotherincoming line to its corresponding tube, while the ignition of such tubetakes place between its counter-electrode and another of its electrodeswhich is connected with an outgoing line not occupied at the sameinstant.

ERIK WALDEMAR HULLEGARD.

REFERENCES CITED I The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Mohr Aug. 10, 1943

